Non-overlapping portions are formed at the left edge portion of a left picture and the right edge portion of a right picture of stereo slide films photographed by a stereo camera of the structure that an interval between the optical axes of right and left lenses is fixed in response to the distance of a subject according to the difference of the visual fields of right and left photographing lenses.
Since these non-overlapping portions do not contribute to forming a solid image to obstruct the view when the stereo slide films are viewed by using a stereo slide viewer, the windows of the pictures of the stereo slide mount have been generally formed in a width narrower than the one picture of the stereo slide film to mask the outer non-overlapping portions of the right and left pictures.
To obtain natural stereo effect, it is also known to need to correct the position of a subject by masking the outsides of the picture of right and left stereo slide films so that the subject (particularly in the case of large influence of the subjects in a close-range view) for mostly affecting the influence to the matching of right and left images in the pictures are disposed nearly at the equal positions on the right and left pictures. That is, when all subjects like a mountain photograph are located nearly at infinitely remote distance, it is not almost necessary to mask the outsides of the pictures, but the near the distance of a subject is disposed, the more the portions to be masked are increased.
The present applicant has proposed a stereo camera that was so formed that the distance between the optical axes of right and left photographing lenses could be adjusted. According to this stereo camera, the distance between the optical axes of the photographing lenses is automatically or manually adjusted in response to the distance of the subject at the time of taking a photograph to suitably correct a parallax. Therefore, it does not almost need to mask the outsides of right and left pictures of the films photographed by the inter-optical axis distance adjusting type stereo camera by the stereo slide mount, but when the subject which strongly affects the influence to the matching of right and left images is photographed at a closer range than a focal distance, it might need to correct a sense of distance by slightly masking the outsides of the right and left pictures.
As mentioned above, the stereo slide films are mounted by adjusting the masking amounts of the outsides of the pictures by varying the interval between the right and left films in response to the distance of the subject or selecting the stereo slide mount of the width of the picture windows to be considered suitably from a plurality of types of stereo slide mounts having different widths of the picture windows, and hence the mounting operation becomes cumbersome and inefficient.
It is not easy to determine suitable masking amounts, the selection of the stereo slide mount and the adjustment of the interval between the films are easily mistaken, and there arises a problem that it is not easy to mount the stereo slide films in an optimum stereo effect state.
Therefore, in order to facilitate the determination of accurate masking amount and the selection of conforming stereo slide mount, it becomes necessary to solve a technical assignment. The object of the present invention is to solve this technical assignment.